GCN Circular 42641
Subject
GRB 251111A: SVOM/VT optical observations with VHF data
Event
Date
2025-11-11T09:01:37Z (2 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
C. Wu (NAOC), J. T. Palmerio (CEA), L.P. Xin (NAOC), H.L. Li, Y. L. Qiu, Yehao Cheng (SWIFAR,YNU), Boting Wang(YNAO) report on behalf of the SVOM team.
SVOM/VT performed an automatic slew on the burst of GRB 251111A (sb25111101) triggered by SVOM/ECLAIRs (Cheng et al. GCN 42637). SVOM/VT began observing the field automatically at 2025-11-11T06:01:57 UTC, 51.65 minutes after the T0, with the slew of the platform triggered on-board, in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
We confirm the detection of the source reported by López-Cámara et al. (GCN 42638) and Wu et al. (GCN 42639) in the VT_R band with the downlinked VHF data.
The AB magnitude was derived as follows:
--------------------------------------------
(T-T0)_mid exptime band mag
54.15 min 300 sec VT_R 21.32 +/-0.11
No correction for Galactic extinction was applied to the photometry.
This result is consistent with the report by Zheng et al. (GCN 42640)
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.